Two-stage continuous carbonization activation process



Jan. 2, 1951 K. B. STUART 2,536,782

TWO-STAGE CONTINUOUS CARBONIZATION ACTIVATION PROCESS Filed March 4, 1948 INVENTOR 40 AE/VNFTH 84870 fit/ART 4/ ATTORNEYS Patented Jan. 2, 1951 TWO-STAGE CONTINUOUS CARBONIZATI ACTIVATION PROCE Kenneth B. Stuart, Denver, 0010., assignor toThe Colorado Fuel & Iron Corporation, acorporation of Colorado Application March 4, 1948, Serial No. 1'2 ,963

11 Claims.

This invention relates to method of. producing activated carbon and has for its object certain improvements in such method for producing activated carbon of uniform high quality.

Inthe production of activated carbon, it is customary first to char or carbonize suitable raw carbonaceous material and then to activate it, usually with a'hot mildly-oxidizing gas, such as superheated steam. To this end, the activating gas-is'pas'sedinto a column of previously charred carbonaceous material. The gas tends to channel its way through-the column of char, following the line of -lcast-resistance, with the result that thechar is-not uniformly activated.

Investigations confirm my discovery that a methoctmay be employed in which the carbonaceousmaterialmay be successively carbonized and activated, the steps of the method being so arranged as to assure. substantially uniform dis tribution ofthe carbonizing and activating gases amonglthesolid-particles of carbonaceous material. -.In this way each carbon particle receives substantiallythesametreatment.

The apparatus employed comprises an upright retort with an inletatthe top for ingress of carbonaceous material and, an outlet at the bottom for egress of..activ.ated carbon the retort being :divided into. an uppercarbonizing chamber and a lower activating chamber with a partition disposed-between the two chambers .withiat least one openingtherein for the passage downwardly of char; from the upperchamber to the lower chamber andfor. the passage upwardly of gases from thelower chamber to the upper chamber. An automatic pressure controlled valve outlet. extends through the wall of the retort and iconnectsthe upper portion of, the upper chamber for. the passage of exhaust gases from, the .retort.

,A manifold; is advantageously disposed in the upper portion-of the lower chamber, an inlet ex- ,tending, through the wall of the retort and connecting'the manifold for the passage of activating gas into the manifold. A plurality of spaced and perforateddown-pipesdepend from the manifold deeply into the. lower chamber for the passage .of activatinggas from the-manifold to the lower chamber. eAnother manifold is disposed in the upper portion of the upper chamber, with one or morerconduitsconnecting the upper portion of the lower chamber with the latter manifold. A

plurality ,oflspaced and perforated. down-pipes depend from the latter manifold deeply into the upper chamber for the passage of carbonizing gasesfrom thelatterwmamfold into the upper chamb r.

The partition between the two chambers is also advantageouslyin the form of a hopper depending'into the lower chamber'to" provide an" open spacein the upper portion above the normal level of carbon confined in the lower chamber'to reduce the velocity 'of gases sweeping through the retort, thereby permitting the dropping of suspended fines. The upper portion 'ofthe lower chamber is preferably'substantially greate'r'i'n cross-sectional area than themain portion" of the chamber to provide an enlarged space. This space may be regarded as a detention zonein which the velocitybf' thegas is 're'duc'ed to drop the suspendedfihes while at'thesa'inetime keeping the hot gas inthe detention zone in direct contact andheat interchange relationship with the carbonto helfiprovi'de the marneee sary to effect the desired activation.

The inlet at" the 'top of the retort is preferably in the form of a conduit depending into the upper chamber to providea'n open space'above the normallevel of carbon'con'finedin the upper chamher to reduce the velocity of gases rising 'upwardly through the retort and'thereby"permitting the dropping-of suspended fines. with the lower chamber, the upper'portionof the upper chamber is preferably substantially greater in cross-sectional 'area than theinain portion of the chamber to provide additional space. This space also'functionsas a detention zone in whichthe velocity ofthe gases is reduced and suspended {fines carried bythefgas'es are dropped asthey sweep through theca rborfiaing zone. While inthe detention zone,"the still hot gases are in direct contact and hence in heat interchange relationship with the carbon to help provide the heat necessary to effect the desired carbonization.

I Sothat the carbon'izing and activating steps may be conducted under pressure, the inlet'at the top of the retort communicates with 'a' charge chamber, a valve being'lfdispojs'ed}betweenthe charge chamber and the inlet'to'openandclose the passageway between'the two. With an arrangement such'as this; the valve may be opened to permit the passage of afcharg'e'of the raw carbonaceous material irlto' the retort, after which the valve may be closedto prevent the escape of exhaust gases by way of" the charge chamber. Exhaust-gases are'bled from the retort through the automatic pressure controlled valve outlet leading from theupper chamber.

The outlet at'the bottom of the retort coinmunicates' with a cooling chamber, a valve ing disposed between the outlet and'the cooling 3 chamber to open and close the passageway between the two. A star discharge is preferably located at the outlet to transfer activated carbon from the retort to the cooling chamber. With the valve closed, pressure conditions may be maintained within the retort. From time to time the valve may be opened and the star discharge operated to transfer activated carbon from the retort to the cooling chamber, after which the valve is again closed to restore the desired pressure conditions within the retort.

In accordance with the method of the invention, a continuous body of finely divided carbonaceous material is advanced through a carbonizing zone, a constricted passageway and an activating zone, the particles of char moving relatively toone another as they pass through the constricted passageway to efiect their mixing. Hot activating gas under substantial positive pressure is passed through the char in the activating zone. Hot gases from the activating zone While still under substantial positive pressure are passed through the carbonaceous material in the carbonizing zone and into a gas detention zone directly above its normal level in the zone. The velocity of the gases is reduced as they enter the' detention zone to drop suspended carbon fines carried by the gases as they sweep through the body of carbon. While in the detention zone the gases are kept in direct contact and hence in heat-interchange relationship with the carbon to help provide the heat necessary to effect the desired carbonization. And the exhaust gases are withdrawn from the detention zone while maintaining all of the zones under substantial positive pressure.

In a presently preferred practice, hot gases from the activating zone are passed into a gas detention zone directly above the normal level of the char in the activating zone. of the gases is reduced as they enter the latter detention zone to drop suspended fines carried by the gases as they sweep through the activating zone. While in the latter detention zone, the hot gases are kept in direct contact and hence in heat-interchange relationship with the carbon to help provide the heat necessary to effect the desired activation. Also, the hot activating gas is preferably released in a plurality of small streams at a plurality of points distributed throughout the char in the activating zone to get a substantially even distribution of the gas. It is preferred similarly to release hot gases from the activating zone in a plurality of streams at a plurality of points distributed throughout the char in the carbonizing zone.

These and other features of the invention will be better understood by referring to the accompanying drawing, taken in conjunction with the following description, which diagrammatically shows an apparatus that may be employed in a practice of the invention.

The apparatus shown comprises a retort ii) having a heavy outer insulating jacket H. The retort stands in an upright or vertical position and is generally cylindrical in plan, being divided into an upper or carbonizing chamber i2 and a lower or activating chamber 13. The two chambers are separated by a partition in the form of a hopper M with a depending outlet 55 to pro- ;vide an open space in the upper portion of the lower chamber above the normal level of carbon confined in that chamber. The upper portion of the lower chamber is in the form a bulged- The velocity v out or enlarged section I8, making it substan tially greater in cross-sectional area than the main portion of the chamber, to provide additional open space in the upper portion of the lower chamber. The lower portion of the lower chamber is in the form of an inverted frustoconical section or hopper 19, with a depending outlet 28. The top of the retort is fitted with a depending inlet 22 to provide an open space in the upper portion of the upper chamber. The upper portion of the upper chamber is in the form of a bulged-out or enlarged section 23, making it substantially greater in cross-sectional area than the main portion of the chamber, to provide additional open space in the upper porticn of the upper chamber.

A manifold 25, generally annular in shape, is disposed horizontally directly below the side wall of the hopper IQ and around depending outlet i5 in the open space in the upper portion of lower chamber 13. An inlet 28 extends through the Wall of the retort and connects the manifold for the passage of activating gas into the manifold. A plurality of spaced and perforated down-pipes 2i depend from the manifold deeply into the lower chamber for the passage of activating gas from the manifold to the lower chamber. The number of down-pipes and perforations is such as to assure a substantially even distribution of the activating gas in the body of char undergoing activation in the lower chamber.

A second manifold 38, also generally annular in shape, is disposed horizontally directly below the top wall of the retort and around depending inlet 22 in the open space in the upper portion of upper chamber l2. As shown, the manifold is supported on the side wall of hopper M by means of three vertical pipes 3| spaced at angles. A plurality of spaced and perforated down-pipes 32 depend from the manifold deeply into the upper chamber for the passage of gases into the upper chamber from the manifold. The number of down-pipes and their perforations is such as to assure a substantially even dispersion of exhaust gases to the carbon undergoing charring in the upper chamber. A valved outlet 33 extends through the wall of the retort for the controlled passage of exhaust gases from the retort.

Inlet 22 at the top of the retort connects with a charge chamber 35 and a measuring bin 36, a valve 31 being interposed between the measuring bin and the charge chamber. A similar valve 33 is disposed between the charge chamber and the inlet of the retort.

Outlet 2E3 at the bottom of the retort connects with a charge chamber 40 fitted with an openable closure ii. In the specific construction shown, a star discharge 52 is associated with the outlet of the retort to facilitate removal of activated carbon therefrom. A valve 43 is interposed between the star discharge and the charge chamber.

The apparatus may be operated as follows:

Suitable carbonaceous material, such as finely divided anthracite coal, is fed into retort it until lower activating chamber i3 and upper carbonizing chamber I2 are filled. To this end, valve 43 is closed and valves 38 and 31 are opened, carbon being passed successively through measuring bin 35, and charge chamber 35, into the retort. When the lower and upper chambers are filled, valve 33 is closed.

Suitable activating gas is passed underpositive pressure through valved inlet 26 into manifoldlirandthenthro sh perforated dowurp ses 2.1. into. the bodyof, har; onfined. DTHQW IQ 19JD7 ber i131. Dueto the.-.substan.t a 1 :ev.endis r bution of the. relatively large n mbe of pe f ate down-pipes... the activa n a s. ased; sub; stanti lly. evenly. throu o body. Q-f: 1 4; The hotgas :ris s,up -r rdly nthelower chamber in. sweepin c ta wi hv e: pa ti les, f. h un il it reaches; t p c n. hulseeu i e iqn B, abo ue,the toplevel of the bodyotchar. Th's space ,may be considereda gas detention zone reetly-abovethenormalflevel of the chari activating; zone, The; velocity 'of the ga ducedas tn er hei etent n ne a suspended; f nes carreid, by the gas as itsweeps upwardly through" the-activating zone. While the hot gas is inthe detention :zone, it remains in recto est a sas n twar i slatifinsl' ip, with the carbon, to help provide the heat necessary to; efiect the..des ired. actiyation.

he ot a s n, s o eten ion. nd ecui ne While-. i lL dbste tial-positi-ve pressure, through pipes, Blintouppermanifoldv 3E and thenenter perforated dow npipes 32. Due to thefsubstantially ever distribution of the; relatively large number oi perfo: rateddown-pipes, the spent activating; gases-are distributed substantially; evenly throughout the body of char. The-gases risecompletely through thebody ofchar and enter bulgedout section 23- to the space above thenormal level of the body of char confined in; the upperchamber. This space may also be regarded as a detention zone, in whichthe velocity of the gases isreduced to permit the dropping of suspended fines carried by, the gases. The still hot gases in thedetention zone arekept indirect contact, and hence; in heat interchange relationship, with the char tohelpw provide the heat necessary to effect the; desired carbonization. The spent or exhaust gases pass out of valved outlet 33 while still under substantial positive pressure.

Activation of carbon in the lower chamberand charring of carbon in, the upper: chamber take place simultaneously. When the char in the lower chamber, particularly the lower portion of the lower chamber, is suitably activated dis; chargew valve 43 is opened and star-discharge 42 is operated to withdraw.activatedcarbon from thelower chamber to cooling chamber Mi..- As this. .occurs, the char abovein boththelower and upper. chambers settles, or .moves downwardly,- thus leaving space in the upper portion of the upperchamber for additional carbon. After a desired amountof activatedcarbon is withdrawn, rotationof the star discharge isterminated and the discharge valve is closed; and after. the activatedscarbon. is; cooled, closure. 4| is opened. to remove the carbon.

Additional carbonaceous material is placed in -measuring bin 3fi andl passed into charge chamber 35'.- Valve 31 is: closed and, valve 38 is opened to drop the material through inlet 22- into the lower chamber.

The discharging and charging operations are conducted intermittently; The material in the upper and'lower chambers ineffect forms a com tinuous colui nn vvhic'h is progressively advanced by; gravity through the'retort' Due tothe controlled manner 'in' which the activating gas is introduced and the spent gases are withdrawn, the activating andcarbonizing steps may be conducted under suitable pressure conditions. As the particles of carbon move downwardly through bulged-out section 23'; and: rub against downipes. 3,2, and the side wall; of. the upper; chamber and: pass into restricted-passa eway I25. at the bottomofhopper M, agentlemixing; c: tion is ,obtained-. This mix ing actionds; continued as the. charred carbon particles move through the restricted passageway and, spread laterally;

across the retort, and ast'hey move downwardly through bulged-out section i 8 and rub against.

chamber and the upper or carbonizing chamberand these solids would soon clog restricted open ings if means Were notprovided todrop them out of they gas stream. These means. comprisethe bulged-out or expanded sections, the depending inlet and the hopper or funnel with itsdepending outlet between the two chambers. In thesepore tions of the apparatus, the velocity of the gases is reduced to a point where the solids drop out. Another desirable feature of the apparatus is that the retort as a Whole, contains substantially nodead space, in which to hold upmovementot thematerial. The structure shownis such, asto. insuresubstantially uniformcharring and activag tion of thecarbon. Q

Activating gases of various kinds may h reinployed. Themost common aresteamand carbon dioxide, or. both. Activating. gas may be ob.- tained, forexample, by burning, 'combus'ti-b1e.;gas, under pressure in air. The activating stepl is conducted under positivev pressure, thatlis superatmospheric pressure. This may vary over a ra ther wide range but should besubstantial, pref,- erably inexcess of 5. pounds per square inch gauge pressure. I have had excellent. results with pressures in the neighborhood of .20 pounds: per square inch gauge press-me. The. pressure must, however, be consistent with safety, depend.-. ing upon the strengthof the apparatus.

Similarly, carbonizing gasespr" various, kinds may be employed. It iseconc-mical tousethe gases from theactivating step for thecarbonizing step, as described.v It. is also preferable toconduct the carbonizing, step; under a.,.substantia-l positive pressure, say .olthe same order as in the activating step. 1

The -fiow. of activatingand carbonizing gases through the lower and upper ,chamhers should besubstantial and may, of course, vary over arather widerange. I have, for example-passed activating, gas in contact with the char at a tem perature of about 1400? F. to about, 1600 3. and at a rate of about to 240standard cubic feet ofgas. per. hour per 1. to 2 pounds otactivated carbon produced from the char; and carbonizing gas in contact with the carbon (Colorado-sub-bi; tuminous coal) at the rate of about 2500to 6000 standard cubic feetof gas per 25 to 50 poundsofchar per hour. Activation and carbonizationv oil the carbon may be effected in a numberof-ways, such for example. as, described, in my copending application Serial No. 501,044, filed September 3, 1943, now U. S. 2,501,700.,

It Will be clear to those skilled in this art that the practice of the,. invention lends. itself. to. a number of useful modifications.

I. claim;

1. In the method of producing activated caret.

bon, the improvement which comprises progressively advancing a continuous body of finely divided carbonaceous material through a carbonizing zone, a constricted passageway and an activating zone, the particles moving relatively to one another as they pass through the constricted passageway to effect their mixing, passing hot activating gas under substantial positive pressure through the char in the activating zone, passing hot gases from the activating zone while still under substantial positive pressure through the char in the carbonizing zone and into a gas detention zone directly above the normal level of the char in the carbonizing zone, reducing the velocity of the gases as they enter the detention zone to drop suspended carbon fines carried by the gases as they sweep through the body of char, keeping the gases while in the detention zone in direct contact and hence in heat-interchange relationship with the char to help provide the heat necessary to eilect the desired carbonization, and withdrawing exhaust gases from the detention zone while maintaining all of the zones under substantial positive pressure.

2. Method according to claim 1, in which hot gases from the activating zone are passed into a gas detention zone directly above the normal level of the char in the activating zone, reducing the velocity of the gases as they enter the latter detention zone to drop suspended fines carried by the gases as they sweep through the activating zone, and keeping the hot gases while in the latter detention zone in direct contact and hence in heat-interchange relationship with the char to help provide the heat necessary to efiect the desired activation.

3. Method according to claim 1, in which the hot activating gas is released in a plurality of small streams at a plurality of points distributed throughout the char in the activating zone to get a substantially even distribution of the gas, and in which hot gases from the activating zone are passed into a gas detention zone directly above the normal level of the char in the activating zone, reducing the velocity of the gases as they enter the latter detention zone to drop suspended fines carried by the gases as they sweep through the activating zone, and keeping the hot gases while in the latter detention zone in direct contact and hence in heat-interchange relationship with the char to help provide the heat necessary to efiect the desired activation.

4. Method according to claim 1, in which the hot activating gas is released in a plurality of small streams at a plurality of points distributed throughout the char in the activating zone to get a substantially even distribution of the gas, and hot gases from the activating zone are released in a plurality of streams at a plurality of points distributed throughout the char in the carbonizing zone to get a substantially even distribution of the gases.

5. Method according to claim 1, in which a portion of the hot gases is passed from the activating zone through the relatively small body of char in the constricted passageway into the carbonizing zone, and another portion of the hot gases is withdrawn from the body of char in the activating zone at a plurality of points and passed into the carbonizing zone.

6. Method according to claim 1, in which a portion of the hot gases is passed from the activoting zone through the relatively small body of char in the constricted passageway into the car bonizing zone, and another portion of the hot gases is withdrawn from the body of char in the activating zone at a plurality of points and released at a plurality of points throughout the body of char in the carbonizing zone to get a substantially even distribution of the gases.

'1. In the method of producing activated carbon, the improvement which comprises passing hot activating gas under substantial positive pressure through a body of finely divided char in an activating zone, passing hot gases from the activating zone while still under substantial pressure through a body of finely divided carbonaceous material in a carbonizing zone and into a gas detention zone directly above the normal level of the material in the carbonizing zone, reducing the velocity of the gases as they enter the detention zone to drop suspended carbon fines carried by the gases as they sweep through the body of material, keeping the gases while in the detention zone in direct contact and hence in heatinterchange relationship with the material to help provide the heat necessary to effect the desired carbonization, and withdrawing exhaust gases from the detention zone while maintaining all of the zones under substantial positive pressure.

8. Method according to claim '7, in which hot gases from the activating zone are passed into a gas detention zone directly above the normal level of the char in the activating zone, reducing the velocity of the gases as they enter the later detention zone to drop suspended fines carried by the gases as they sweep through the activating zone, and keeping the hot gases while in the latter detention zone in direct contact and hence in heat-interchange relationship with the char to help provide the heat necessary to efiect the desired activation.

9. Method according to claim 7, in which the hot activating gas is released in a plurality of small streams at a plurality of points distributed throughout the char in the activating zone to get a substantially even distribution of the gas, and

'- hot gases from the activating zone are released in a plurality of streams at a plurality of points distributed throughout the body of material in the carbonizing zone to get a substantially even distribution of the gases.

10. In the method of producing activated carbon, the improvement which comprises progressively advancing a continuous body of finely divided carbonaceous material through a carbonizing zone, a constricted passageway and an activating zone, the particles moving relatively to one another as they pass through the constricted passageway to efiect their mixing, passing hot activating gas under substantial positive pressure through the char in the activating zone and into a gas detention zone directly above the normal level or material in the carbonizing zone, reducing the velocity of the gases as they enter the detention zone to drop suspended carbon fines carried by the gases as they sweep through the body of material, keeping the gases while in the detention zone in direct contact and hence in heat-interchange relationship with the char to help provide the heat necessary to efiect the desired activation, passing hot gases from the activating and detention zones while still under substantial positive pressure through the body of material in the carbonizing zone, and withdrawing exhaust gases from the carbonizing zone while maintaining all of the zones under sub-i 7s s e ti l p i epres ure 11. Method according to claim 10, in which the hot activating gas is released in a plurality of small streams at a plurality of points distrib uted throughout the char in the activating zone to get a substantially even distribution of the gas, and in which hot gases from the activating and detention zones are released in a plurality of streams at a plurality of points distributed through the body of material in the carbonizing zone to get a substantially even distribution of the gases.

KENNETH B. STUART.

REFERENCES CITED The following references are of record in the file of this patent:

Number Number Certificate of Correction Patent No. 2,536,782 January 2, 1951 KENNETH B. STUART It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows:

Column 10, line 14, list of references cited, under FOREIGN PAT- ENTS for d 189,667 Great Britain July 5, 1932 rea 189,148 Great Britain Feb. 20, 1.924 and that the said Letters Patent should be read as corrected above; so that the same may conform to the record of the case in the Patent Oifice.

Signed and sealed this 6th day of March, A. D. 1951.

THOMAS F. MURPHY,

Assistant Commissioner of Patents. 

1. IN THE METHOD OF PRODUCING ACTIVATED CARBON, THE IMPROVEMENT WHICH COMPRISES PROGRESSIVELY ADVANCING A CONTINUOUS BODY OF FINELY DIVIDED CARBONACEOUS MATERIAL THROUGH A CARBONIZING ZONE, A CONSTRICTED PASSAGEWAY AND AN ACTIVATING ZONE, THE PARTICLES MOVING RELATIVELY TO ONE ANOTHER AS THEY PASS THROUGH THE CONSTRICTED PASSAGEWAY TO EFFECT THEIR MIXING, PASSING HOT ACTIVATING GAS UNDER SUBSTANTIAL POSITIVE PRESSURE THROUGH THE CHAR IN THE ACTIVATING ZONE WHILE PASSING HOT GASES FROM THE ACTIVATING ZONE WHILE STILL UNDER SUBSTANTIAL POSITIVE PRESSURE THROUGH THE CHAR IN THE CARBONIZING ZONE AND INTO A GAS DETENTION ZONE DIRECTLY ABOVE THE NORMAL LEVEL OF THE CHAR IN THE CABONIZING ZONE, REDUCING THE VELOCITY OF THE GASES AS THEY ENTER THE DETENTION ZONE TO DROP SUSPENDED CARBON FINES CARRIED BY TE GASES AS THEY SWEEP THROUGH THE BODY OF CHAR, KEEPING THE GASES WHILE IN THE DETENTION ZONE IN DIRECT CONTACT AND HENCE IN HEAT-INTERCHANGE RELATIONSHIP WITH THE CHAR TO HELP PROVIDE THE HEAT NECESSARY TO EFFECT THE DESIRED CARBONIZATION, AND WITHDRAWING EXHAUST GASES FROM THE DETENTION ZONE WHILE MAINTAINING ALL OF THE ZONES UNDER SUBSTANTIAL POSITIVE PRESSURE. 